This application requests funds to support a central shared facility to determine the crystal and molecular structures of single crystals of organic, inorganic, and biological compounds for an active group of researchers in the Department of Chemistry at MIT. The facility will mainly serve a group of major users who currently hold active NIH research grants. In addition, a service facility will be set up to determine structures for several inorganic chemists who are not supported by NIH who would make good use of the facility.